1. Field of the Invention
The present invention relates generally to medical instrumentation, and more particularly, to a multi-modality ablation device.
2. Prior Art
Ultrasonic and radio frequency instruments are well known in the medical arts. Such instrumentation may be used to make lesions in tissue, but are also used to cut and coagulate tissue and blood, respectively. Typically, ultrasonic instrumentation has an ultrasonic transducer at a working end of the instrument, while radio frequency instruments have one or more electrodes at a working end of the instrument. Each of the working ends is typically separated from a handle or other manipulation means by an elongated shaft.
Instruments utilizing radio frequency energy perform well for single-sided ablation of thin tissue. However, this modality can only ablate thicker tissue at the expense of lesion width. Creating wider lesions with radio frequency energy may result in damage to critical peripheral tissue structures. Beyond 6 mm in tissue depth, radio frequency energy may not achieve lesion transmurality. On the other hand, instruments utilizing ultrasound energy perform well for thick tissue ablation because the energy can be focused into the depth of the tissue. However, for thin tissue, ultrasound may be ineffective as the ultrasound energy is focused in blood, not in the tissue.
Thus, the surgeon must determine the efficacy of the lesion created with one of the ultrasound or radio frequency instruments and may need to exchange instrumentation to create a proper lesion, all of which significantly increase the time of the procedure (ablation cycle time).